The present invention relates to an image producing apparatus and, particularly, to such an apparatus which uses a solid state image sensor and can always take a picture of an object with an adequate exposure time to produce an image.
A chemiluminescent detecting system is known, which comprises the steps of selectively labeling a fixed high molecular substance such as a protein or a nucleic acid sequence with a labeling substance which generates chemiluminescent emission when it contacts a chemiluminescent substance, contacting the high molecular substance selectively labeled with the labeling substance and the chemiluminescent substance, photoelectrically detecting the chemiluminescent emission in the wavelength of visible light generated by the contact of the chemiluminescent substance and the labeling substance and producing digital image signals, effecting image processing thereon, and reproducing a chemiluminescent image on a display means such as a CRT or a recording material such as a photographic film, thereby obtaining information relating to the high molecular substance such as genetic information.
Further, a fluorescence system using a fluorescent substance as a labeling substance is known. According to this system, it is possible to study a genetic sequence, the expression level of a gene and the metabolism, absorption, excretion path and state of a substance introduced into a test mouse and to effect separation or identification of protein or estimation of the molecular weight or properties of protein or the like. For example, this system can perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis after a fluorescent dye was added to a solution containing a plurality of DNA fragments to be distributed or distributing a plurality of DNA fragments on a gel support containing fluorescent dye or dipping a gel support on which a plurality of DNA fragments have been distributed by means of electrophoresis in a solution containing fluorescent dye, thereby labeling the electrophoresis-distributed DNA fragments, exciting the fluorescent dye by a stimulating ray to cause it to release a fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the DNA on the gel support. This system can also perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis, denaturing the DNA, transferring at least a part of the denatured DNA fragments onto a transfer support such as a nitrocellulose support by the Southern-blotting method, hybridizing a probe prepared by labeling target DNA and DNA or RNA complementary thereto with the denatured DNA fragments, thereby selectively labeling only the DNA fragments complementary to the probe DNA or probe RNA, exciting the fluorescent dye by a stimulating ray to cause it to release a fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This system can further perform a process including the steps of preparing a DNA probe complementary to DNA containing a target gene labeled by a labeling substance, hybridizing it with DNA on a transfer support, combining an enzyme with the complementary DNA labeled by a labeling substance, causing the enzyme to contact a fluorescent substrate, transforming the fluorescent substrate to a fluorescent substance having a fluorescent light releasing property, exciting the thus produced fluorescent substance by a stimulating ray to release fluorescent light, detecting the fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This fluorescence detecting system is advantageous in that a genetic sequence or the like can be easily detected without using a radioactive substance.
In the case where such chemiluminescent emission or fluorescent light is detected by a solid state image sensor to produce a chemiluminescent image or a fluorescent image, since chemiluminescent emission or fluorescent light is very weak, the solid state image sensor has to be exposed thereto for a long time. When exposing the solid state image sensor, if the exposure time is too long, an overexposed image is obtained and, on the other hand, if the exposure time is too short, an underexposed image is obtained. In either case, a desired image cannot be obtained and it is necessary to take another picture with a different exposure time. However, it is inefficient to again take a picture. In particularly, the intensity of chemiluminescent emission generated by the contact of the chemiluminescent substance and the labeling substance falls with time elapse and the amount of chemiluminescent emission becomes insufficient. Therefore, when the need arises to take anther picture because of an improper exposure time, the process has to be restarted from the first step of selectively labeling the high molecular substance with the labeling substance. Such operation is extremely troublesome.
Similar problems occur when very weak light is detected by a solid state image sensor to produce an image for observing a heavenly body or the like.
It is therefore an object of the present invention to provide an image producing apparatus which uses a solid state image sensor and can always take a picture of an object with a proper exposure time to produce an image.
The above and other objects of the present invention can be accomplished by an image producing apparatus comprising imaging means having a solid state image sensor for producing image data, exposure control means for starting and stopping exposure of the solid state image sensor at predetermined times, image data storing means for storing image data produced by the imaging means, image processing means for adding the image data produced by the imaging means to the image data stored in the image data storing means every time the exposure of the solid state image sensor is stopped by the exposure control means and storing the thus obtained image data in the image data storing means, and image displaying means for displaying an image on display means based on the image data stored in the image data storing means.
In a preferred aspect of the present invention, the imaging means is constituted as a cooled CCD (charge coupled device).
In a further preferred aspect of the present invention, the image producing apparatus further comprises input means through which the predetermined times can be determined.
In a further preferred aspect of the present invention, the imaging means further comprises an image intensifier in front of the solid state image sensor.
The present invention can be effectively applied to detect very weak light by the imaging means having the solid state image sensor and produce an image and, be particularly effectively applied to produce a chemiluminescent image or a fluorescent image by irradiating an image carrier carrying an image of a fluorescent substance with a stimulating ray and detecting fluorescent light emitted from the fluorescent substance.
In a further preferred aspect of the present invention, the image producing apparatus further comprises a light emitting diode stimulating ray source for emitting a stimulating ray whose center wavelength is between 400 nm and 700 nm.
In a further preferred aspect of the present invention, the image producing apparatus further comprises a light emitting diode stimulating ray source for emitting a stimulating ray whose center wavelength is between 400 nm and 550 nm.
In the present invention, examples of the fluorescent dye stimulable by light emitted from the light emitting diode stimulating ray source and having a wavelength of 400 to 700 nm include Fluorescein (C.I. No. 45350), Fluorescein-X indicated by the structural formula (1) shown below, YOYO-1 indicated by the structural formula (2), TOTO-1 indicated by the structural formula (3), YO-PRO-1 indicated by the structural formula (4), Cy-3 (registered trademark) indicated by the structural formula (5), Nile Red indicated by the structural formula (6), BCECF indicated by the structural formula (7), Rhodamine 6G (C.I. No. 45160), Acridine Orange (C.I. No. 46005), SYBR Green (C2H6OS), Ethidium Bromide indicated by the structural formula (9), Texas Red indicated by the structural formula (10), Propidium Iodide indicated by the structural formula (11), POPO-3 indicated by the structural formula (12), Quantum Red, R-Phycoerrythrin, Red 613, Red 670, Fluor X, FAM, AttoPhos, Bodipy phosphatidylcholine, SNAFL, Calcium Green, Fura Red, Fluo 3, AllPro, NBD phosphoethanolamine, Carboxyrhodamine (R6G), JOE, HEX, Ethidium homodimer, Lissamine rhodamine B peptide, Cy-5 (registered trademark) indicated by the structural formula (8), Allphycocyanin and the like.
In the present invention, examples of the fluorescent dye stimulable by light emitted from the light emitting diode stimulating ray source and having a wavelength of 400 to 550 nm include Fluorescein (C.I. No. 45350), Fluorescein-X indicated by the structural formula (1) shown below, YOYO-1 indicated by the structural formula (2), TOTO-1 indicated by the structural formula (3), YO-PRO-1 indicated by the structural formula (4), Cy-3 (registered trademark) indicated by the structural formula (5), Nile Red indicated by the structural formula (6), BCECF indicated by the structural formula (7), Rhodamine 6G (C.I. No. 45160), Acridine Orange (C.I. No. 46005), SYBR Green (C2H6OS), Ethidium Bromide indicated by the structural formula (9), Texas Red indicated by the structural formula (10), Propidium Iodide indicated by the structural formula (11), POPO-3 indicated by the structural formula (12), Quantum Red, R-Phycoerrythrin, Red 613, Red 670, Fluor X, FAM, AttoPhos, Bodipy phosphatidylcholine, SNAFL, Calcium Green, Fura Red, Fluo 3, AllPro, NBD phosphoethanolamine, Carboxyrhodamine (R6G), JOE, HEX, Ethidium homodimer, Lissamine rhodamine B peptide and the like. 
The above and other objects and features of the present invention will become apparent from the following description made with reference to the accompanying drawings.